1. Field of the Invention
The present general inventive concept relates to a method of fabricating an inkjet printhead, and more particularly, to a method of fabricating an inkjet printhead using a simple process.
2. Description of the Related Art
An inkjet printhead is an apparatus that ejects minute ink droplets on desired positions of recording paper in order to print predetermined color images. Inkjet printheads are categorized into two types according to the ink droplet ejection mechanism thereof. The first one is a thermal inkjet printhead that ejects ink droplets due to an expansion force of ink bubbles generated by thermal energy. The other one is a piezoelectric inkjet printhead that ejects ink droplets by a pressure applied to ink due to the deformation of a piezoelectric body.
The ink droplet ejection mechanism of the thermal inkjet printhead is as follows. When a current flows through a heater made of a heating resistor, the heater is heated and ink near the heater in an ink chamber is instantaneously heated up to about 300° C. Accordingly, ink bubbles are generated by ink evaporation, and the generated bubbles are expanded to exert a pressure on the ink filled in the ink chamber. Thereafter, an ink droplet is ejected through a nozzle out of the ink chamber.
FIG. 1 is a schematic cross-sectional view of a conventional thermal inkjet printhead. Referring to FIG. 1, the conventional inkjet printhead includes a substrate 10 on which a plurality of material layers are formed, a chamber layer 20 stacked on the substrate 10, and a nozzle layer 30 stacked on the chamber layer 20. An ink chamber 22 filled with ink to be ejected is formed in the chamber layer 20 and a nozzle 32, through which ink is ejected, is formed in the nozzle layer 30. In addition, the substrate 10 has an ink feed hole 11 to supply ink to the ink chamber 22.
A typical silicon substrate is used as the substrate 110. An insulating layer 12 for insulation between a heater 13 and the substrate 10 is formed on the substrate 10. The insulating layer 12 is typically made of silicon oxide. The heater 13 is formed on the insulating layer 12 to heat the ink of the ink chamber 22 and generate bubbles. An electrode 14 is formed on the heater 13 to apply current to the heater 13. A passivation layer 15 is formed on the heater 13 and the electrode 14 to protect the heater 13 and the electrode 14. The passivation layer 15 is typically made of silicon oxide or silicon nitride. An anti-cavitation layer 16 is formed on the passivation layer 15. The anti-cavitation layer 16 protects the heater 13 from a cavitation force generated when the bubbles vanish and is typically made of tantalum (Ta).
FIGS. 2A through 2D illustrate a conventional method of fabricating the inkjet printhead of FIG. 1. Referring to FIG. 2A, an insulating layer 12 is formed on a substrate 10 and a heater 13 and an electrode 14 are sequentially formed on the insulating layer 12. Then a passivation layer 15 is formed on the insulating layer 12 to cover the heater 13 and the electrode 14 and an anti-cavitation layer 16 is formed on the passivation layer 15. Next, the passivation layer 15 and the insulating layer 12 are sequentially etched, and thus a trench 17 that exposes a surface of the substrate 10 is formed. Then, referring to FIG. 2B, a predetermined material is coated on the structure illustrated in FIG. 2A and is patterned to form a chamber layer 20, which includes an ink chamber 22 as illustrated in FIG. 1. Then, a sacrificial layer 25 is formed to fill the ink chamber 22 and the trench 17, and a top surface of the sacrificial layer 25 is planarized using a chemical mechanical polishing (CMP) method. Next, referring to FIG. 2C, a predetermined material is coated on the top surface of the sacrificial layer 25 and the chamber layer 20 and is patterned, and thus a nozzle layer 30 which includes a nozzle 32 is formed. Next, referring to FIG. 2D, a rear surface of the substrate 10 is etched such that the sacrificial layer 25 is exposed, and thus an ink feed hole 11 is formed. Then the sacrificial layer 25, which is exposed by the ink feed hole 11 and the nozzle 32 is removed, and thus the ink chamber 22 is formed.
However, in the above described method of fabricating an inkjet printhead, several patterning processes are required and the thickness of the chamber layer 20 cannot be easily obtained as desired using the CMP.